Optical potential mapping with a levitated nanoparticle at sub-wavelength distances from a membrane

TL;DR

This paper demonstrates the optical potential mapping of a levitated nanoparticle near a dielectric membrane at sub-wavelength distances, enabling precise force measurements and advancing on-chip levitated optomechanics.

Contribution

It introduces a method to stably trap and map a nanoparticle's optical potential at sub-wavelength distances from a surface.

Findings

Stable trapping at sub-wavelength distances achieved.

Optical potential mapped with interferometric precision.

Potential for measuring short-range forces demonstrated.

Abstract

The controllable positioning of a vacuum-levitated object near a material surface is of importance for studying short-range forces, such as Casimir forces, interfacial friction forces, or gravity in yet unexplored parameter regimes. Here we optically levitate a nanoparticle in a laser beam strongly focused on a dielectric membrane. By investigating the motion of the trapped particle in vacuum, we map the position-dependent optical potential of the particle. We interferometrically measure the distance between the particle and the surface and demonstrate stable trapping in sub-wavelength proximity of the dielectric surface. Our work is important for the development of on-chip levitated optomechanics and for measuring short-range forces at sub-wavelength distances.